PT  - JOURNAL ARTICLE
AU  - Naoki Ikari
AU  - Hirofumi Arakawa
TI  - Identification of a mitochondrial targeting sequence in cathepsin D and its localization in mitochondria
AID  - 10.1101/2023.01.23.524639
DP  - 2023 Jan 01
TA  - bioRxiv
PG  - 2023.01.23.524639
4099  - http://biorxiv.org/content/early/2023/01/24/2023.01.23.524639.short
4100  - http://biorxiv.org/content/early/2023/01/24/2023.01.23.524639.full
AB  - Cathepsin D (CTSD) is a major lysosomal protease harboring an N-terminal signal peptide (amino acids 1–20) to enable vesicular transport from endoplasmic reticulum to lysosomes. Here, we report the possibility of a mitochondrial targeting sequence and mitochondrial localization of CTSD in cells. Live-cell imaging analysis with enhanced green fluorescent protein (EGFP)-CTSD indicated that CTSD localizes to mitochondria. CTSD amino acids 21–35 are responsible for its mitochondrial localization, which exhibit typical features of mitochondrial targeting sequences, and are evolutionarily conserved. A proteinase K protection assay and sucrose gradient analysis showed that a small population of endogenous CTSD molecules exists in mitochondria. These results suggest that CTSD is a dual-targeted protein that may localize in both lysosomes and mitochondria.Competing Interest StatementThe authors have declared no competing interest.